The present invention relates to a stone cutter having a pair of hydraulically activated jaws, wherein a cutting element block of a jaw(s) is made of a plurality of modular cylinder blocks. Each cylinder block houses a hydraulically activated cutting element. After wear each individual cylinder block can be replaced, thus saving replacement of the entire cutting element block.
Stonecutters for cutting rough surfaced stone bodies are well known in the art. U.S. Pat. No. 3,809,049 (1974) to Fletcher et al. discloses a guillotine type stone cutter having an upper jaw which has a plurality of individual cutter units welded to a transverse frame base. The frame base can be detached from the upper jaw for maintenance. However, the individual cutter units cannot be replaced without a welding operation. Fletcher does address the problem of cutting a rock having an uneven top surface by claiming his cutter units can extend their cutting elements three to five inches in order to conform to a rock""s surface. In operation a common manifold pressures all the pistons in the cutting elements to extremely heavy loads in the 8000 to 10,000 pound range. This hydraulic pressure forces each piston against a surface of the rock at varying heights. Then the manifold input is shut thereby equalizing all the pressure in the manifold, in the supply pipes to each cylindrical cutter element, and in the cylinders of each cutter element. Thus, expensive supply pipes are needed to withstand up to 10,000 pounds of pressure. Then the cut is made by powering the upper jaw to move downward.
Problems. with Fletcher""s design include a high cost in labor to replace a worn cutter unit, a high cost in production to cover high pressure hydraulic supply pipes to each cutter unit and an apparent design flaw which would not let a cutting element to fully extend under pressure. It appears that the end cap would explode off at high pressure. Thus, only rocks that were large enough to contact all the cutting elements could be cut.
Other variably extending cutter element systems use an in-line cylinder block design. The cylinder head affixes to the upper jaw. Each cutter element is a piston extending downward in the cylinder head. The common manifold is piped to the individual cylinders. One problem with this old design is the necessity to replace the entire cylinder block at a cost of over $10,000 when a few central cylinders wear out due to the extra wear and tear on the central cutting elements.
The present invention solves several problems in the art including offering a modular cylinder block. Each cutter unit especially the central ones can be disconnected by bolts from the upper jaw and replaced for far less than $10,000. Also each cutter unit is individually valved to disconnect from the manifold once an isostatic state is reached among the cylinders of the cutter elements. Thus, only plastic 250 pound piping is needed to each cutter unit. This saves considerable costs in manufacturing since dozens of cutter units exist on a single machine. Another benefit of the modular bolted on cutter unit design is the ease with which variable width cutting assemblies can be made. Only the transverse mounting bar needs to be custom cut to the width of the stone cutting machine or a subset thereof if desired. Then the proper number of cutter units are bolted on to the transverse bar, and assembly is complete. This is a far less expensive technique than casting a different width cylinder block for each varying width cutter.
The main aspect of the present invention is to provide a modular set of bolt on cutter units to a transverse mounting bar for a jaw of a guillotine type stone cutter.
Another aspect of the present invention is to provide a shut off valve from the manifold for each cutter unit.
Other. aspects of this invention will appear from the following description and appended claims, reference being made to the accompanying drawings forming a part of this specification wherein like reference characters designate corresponding parts in the several views.